Many would like to postulate that there has been some kind of fundamental shift in capitalism's relations and processes since the advent of industrialism, but I would dispute this. It is very easy for people to mistake shifts in capitalism's affects on us as individuals as a change in the system altogether. Take, for instance, the latest crisis of financial capital. It would seem many radicals in North America, especially in the outset of the crisis, hypothesized that it was a "crisis in the heart of capitalism" or that it would lead to some kind of calamitous result for the capitalist relation; and they continue to do so. However, I believe all that is happening is that as accumulated capital goes through a period of destruction (a precedent of the capitalist system) those who were most reliant on what had been afforded to them by what had previously been rendered as productive means experience even deeper suffering and personal crises. The working class's belly and home are entirely dependent on capital's ability to ensure stability in the wage-relation (it can't, but that's besides the point I'm trying to make).
So now you see the ruling class making all of their moves in their employment practices. More desperate and poor people + untenable employment sectors = easy access to temp labor, more hostile fire & hire practices, and the expansion of the service labor sector. Capitalists are making record profits while millions are experiencing the downfall of what America had once cherished as its "middle class"; Greece may be on the precipice of a civil war; Mexico's most productive employment sector is the drug trade, and thousands are suffering even worse for it; Spanish metropolises are veritably falling apart around people's ears... So are "postmodern era economic conditions" fundamentally different from when categories like "working class", "proletariat", "wage-labor", etc., were first coined? Maybe. But the relations established by the capitalist production process have barely changed at all. An existence defined by catastrophe is one of the most fundamental aspects of capitalistic economic conditions and that certainly has not changed at all. Wage-labor is still wage-labor. Unions still launch industrial action and then tell everyone to go back to work when the noise has died down. Capitalists are still capitalists. The ruling ideas of the day are still the ideas of the ruling class. The commodity fetishism still presents the proletarian's activity as way more of a problem than simply "not being given the full economic value of one's labor". So on and so forth. /end of rant